Reactor system and process for wood modification

A reactor system for the acetylation of lignocellulosic materials, the system comprising:

• a reaction vessel having a closable aperture suitable for the introduction of a stack of solid wood and having a diameter of 1 m to 6 m, a length, and a ratio of said length to said diameter of 2-20;
• a vacuum connection suitable for creating vacuum in the reaction vessel;
• a liquid-inlet and/or liquid-outlet for acetylation fluid;
• a gas-inlet and gas-outlet connected to a first gas flow loop, said first gas flow loop comprising a gas flow line connecting the gas-inlet and the gas-outlet, said gas flow line connected to a heat exchanger and at least one fan, wherein the inlet and the outlet of the first gas flow loop are positioned to conduct gas circulation over the diameter of the reaction vessel, wherein at the inlet side for the first gas flow loop, a first gas distribution device is positioned between the inlet and the inside of the reaction vessel;
• a plurality of gas flow loops connecting further inlets and outlets of the reaction vessel, said further inlets and outlets positioned to conduct gas circulation over the diameter of the reaction vessel, said first and further inlets and outlets being divided over the length of the reaction vessel;
• and
• a second gas distribution device between the inside of the reactor and the outlet to the gas flow loops.